Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic...
-
Upload
roland-barton -
Category
Documents
-
view
220 -
download
0
Transcript of Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic...
![Page 1: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/1.jpg)
![Page 2: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/2.jpg)
Description of Waves
The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its:
• period – the time it takes 2 successive wave crests to pass a fixed point
• frequency = 1 / – the number of waves passing a fixed point per second
• wavelength – horizontal distance between two successive wave crests
• wave speed c = /
• wave height H = 2A (A = amplitude) – vertical distance between wave crest and adjacent trough
• wave steepness = H /
![Page 3: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/3.jpg)
Calm water
![Page 4: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/4.jpg)
![Page 5: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/5.jpg)
![Page 6: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/6.jpg)
Ocean waves can be classified in various ways:
Disturbing Force- the forces which generate the waves. 1. Meteorological forcing (wind, air pressure); sea and
swell belong to this category. 2. Earthquakes; they generate tsunamis, which are
shallow water or long waves. 3. Tides (astronomical forcing); they are always shallow
water or long waves.
Wave Classification
![Page 7: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/7.jpg)
Hurricane Andrew- 1992
![Page 8: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/8.jpg)
"Tsunami" - a Japanese word meaning "great wave in harbor". It is a series of ocean waves commonly caused by violent movement of the sea floor by submarine faulting, landslides, or volcanic activity. A tsunami travels at the speed of nearly 500 miles per hour outward from the site of the violent movement.
![Page 9: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/9.jpg)
![Page 10: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/10.jpg)
Fault displacement under water displaces water, water moves to fill vacuum, generating large waves.
Tsunami
![Page 11: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/11.jpg)
Tsunamis struck Kahului in 1946, 1957, 1960, and 1964. The earliest historically recorded tsunami in Kahului occurred on November 7, 1837, when a large tsunami traveled 800 yards inland and destroyed a Hawaiian village.
The 1960 tsunami was caused by a violent earthquake in Chile on May 22, 1960. It took approximately 15 hours for the tsunami to travel from Chile to the Hawaiian Islands. The tsunami killed 61 people in Hilo on the Big Island, but there were no other human casualties on any of the other islands. The tsunami caused moderate damage in Kahului.
MauiPuunene Avenue
Aftermath of a Tsunami in Kahului, 1960
![Page 12: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/12.jpg)
A giant wave engulfs the Hilo pier during the 1946 tsunami. The red arrow points to a man who was swept away seconds later.
![Page 13: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/13.jpg)
![Page 14: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/14.jpg)
Passage of a tsunami as seen in a sea level record from Hilo, Hawaii. The observed sea level shows high frequency variations with a period of approximately 20 minutes and an initial amplitude of nearly two meters (total tsunami wave height 3.7 m)
Earthquake originated in Anchorage, AK
tides w/out tsunami
![Page 15: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/15.jpg)
This mathematical simulation (above) shows the tsunami created by the Cascadia Subduction Zone earthquake on January 26, 1700, as it reaches Hawaii on its way across the Pacific Ocean (5 hrs).
![Page 16: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/16.jpg)
Free Waves, Forced Waves
• Free waves- a wave that is formed by a disturbing force such as a storm. Waves continue to move without additional wind energy
• Forced wave- a wave that is maintained by its disturbing force, e.g., tides
![Page 17: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/17.jpg)
Restoring Force
Force necessary to restore the water surface to flatness after a wave has formed in it
• Capillary waves- wavelength < 1.73 cm
• Gravity waves- wavelength > 1.73 cm
![Page 18: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/18.jpg)
Deep-water, Transitional, & Shallow-water waves
Wavelength- determines the size of the orbits of water molecules within a wave
Water depth- determines the shape of the orbits
Deep-water waves- more circular orbits
Water Depth 1/2 of wavelength
Transitional waves- intermediate-shaped orbits
1/20 wavelength depth ½ wavelength
Shallow-water waves- orbits are more flattened
Water Depth 1/20 of wavelength
![Page 19: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/19.jpg)
![Page 20: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/20.jpg)
Wind Waves- gravity waves formed by the transfer of wind energy into water
• Wave ht- usually <3m
• Wave length- 60-150m
Factors that affect wind wave development:
• Wind strength
• Wind duration
• Fetch- the uninterrupted distance the wind blows
http://www.newportsurf.com/tides.html
![Page 21: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/21.jpg)
Interference and Rogue WavesInterference waves: when waves from different
storm systems overtake one another. They add (constructive interference) or subtract (destructive interference) from the other.
Constructive Destructive Mixed
![Page 22: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/22.jpg)
Rogue waves:
• freak waves that come out of nowhere
• created by constructive interference
• formed by the interaction of a wind wave and a swift surface current
• common in southeastern tip of Africa
![Page 23: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/23.jpg)
Types of Breaking Waves:• Plunging breaker• Spilling breaker• Surging breaker
Factors that determine the position and nature of the breaking wave:• Slope• Contour• Composition
Waves approaching shoreWaves approaching shore
![Page 24: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/24.jpg)
![Page 25: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/25.jpg)
a gradual sloping bottom generates a milder wave
![Page 26: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/26.jpg)
• doesn't break, because it never reaches critical wave steepness
• breaker diminishes in size and looses momentum• Found on beach with a very steep or near vertical
slope
Surging BreakerSurging Breaker
![Page 27: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/27.jpg)
Sunset Beach
What type wave are these?
Waikiki
![Page 28: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/28.jpg)
Wave Refraction- when a wave approaches an inclined surface (shore) from an angle, the wave slows and bends, paralleling the shoreline, creating odd surf patterns
![Page 29: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/29.jpg)
Wave Diffraction- Propagation of a wave around an obstacle
![Page 30: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/30.jpg)
Wave Reflection- a progressive wave striking a vertical barrier and being reflected in the direction from where they came
The Wedge, Newport Harbor, Ca
waves
![Page 31: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/31.jpg)
Rip Current
![Page 32: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/32.jpg)
![Page 33: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/33.jpg)
Internal Waves- at thermocline/pycnocline layer
![Page 34: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/34.jpg)
• constant coral species turnover associated with mortality and recruitment• rarely thicker than a single coral colony
Wave exposed environment:
![Page 35: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/35.jpg)
• Breakage• Scour• Abrasion
Mortality on wave exposed environment due to:
![Page 36: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/36.jpg)
Depth- lack of coral accretion in shallow open ocean coastline due to wave energy
Absence of mature barrier reef in Hawaiian Islands
![Page 37: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/37.jpg)
5 types of open ocean swells that cause disturbance to coral:
Destructive waves-causes high mortality on reef building corals:
1. North Pacific winter waves on north and western coastline
2. hurricane generated swells on south or southwest coastline (40 yr cycle)
![Page 38: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/38.jpg)
Low moderate nondestructive waves- optimizes mixing and nutrient uptake or exchange, usually beneficial due to increased circulation and nutrients between water and organisms:
3. Tradewinds generated from northeast or east; ht. of 1-3 m, occurs 90% of summertime and 55-65% of wintertime
4. Long period southerly swell from southern ocean during the Austral winter; common between April and September (1-2 m in ht)
5. Kona storm generated waves (~4m); occasionally may be destructive and cause beach and shoreline erosion
![Page 39: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/39.jpg)
Reef Front in a Low Energy Environment
![Page 40: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/40.jpg)
Reef Front in a High Energy Environment
Algal RidgeAlgal Ridge
![Page 41: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/41.jpg)
Upper Reef Slope of a High Energy Environment
![Page 42: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/42.jpg)
Upper Reef Slope
![Page 43: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/43.jpg)
Upper Reef Slope of a Lower Energy Environment
![Page 44: Description of Waves The simplest way of looking at waves is the concept of a wave as a harmonic oscillation. It can then be described by its: period.](https://reader035.fdocuments.net/reader035/viewer/2022062314/56649ec15503460f94bcd471/html5/thumbnails/44.jpg)
Site Depth (m)
Coral cover
%
Coral Diversity (H’)
Algal Cover %
Bare Limeston
e %
Sand %
Dominant coral,
algae
Coral growth (mm/y)
Kaneohe Bay
1 2±5 0.16 5 1 95 P.c. Negligible
2-5 69±20
0.35 9 3 19 P.c.M.v
7.66
Hanauma Bay
1 <1 <0.01 90 10 0 P.o. Negligible
12 73±14
0.87 0 5 10 P.c.P.l.
8.13
Mamala Bay
1 6±3 0.15 90 5 5 P.m. Negligible
12 10±5 0.35 2 40 40 P.l 10.1
Sunset Beach
1 9±8 0.53 60 20 20 P.l. Negligible
12 15±13
0.68 20 65 65 P.m. 8.08
P.l.- Porites lobata; P.C.- Porites compressa; M.v.- Motipora verrucosa, P.m.- Pocillopora meandrina; P.o.- Porolithon oncodes (coralline algae)
Table 1. Community structure and growth of coral reef at sites selected for study. Attributes of community structure are based on one 50 m transect at each station. Annual coral growth rates are averages of 10 colonies.